Could you tell me why this code wont delete a node in a BST? Is there any logical error in my code?
// To delete a node from the BST
public Node deleteNode(Node myRoot, int toDel) {
if (myRoot == null) return null;
else if (toDel < myRoot.data) myRoot.left = deleteNode(myRoot.left, toDel);
else if (toDel > myRoot.data) myRoot.right = deleteNode(myRoot.right, toDel);
else {
// Leaf node
if (myRoot.right == null && myRoot.left == null) {
myRoot = null;
} else if (myRoot.left == null) { // No left child
myRoot = myRoot.right;
} else if (myRoot.right==null){ // No right child
myRoot = myRoot.left;
}
}
return myRoot;
}
NOTE :- This code only deletes the nodes with one child or no child. I am currently working on deleting a node with 2 children so please dont solve that for me.
If 0 children, simply delete node (return null for it).
If there is 1 child, simply replace the node with the child that is not null.
public Node deleteNode(Node myRoot, int toDel) {
if (myRoot == null) {
return null;
} else if (myRoot.data == toDel) {
if (myRoot.left != null) {
return myRoot.left;
} else if (myRoot.right != null) {
return myRoot.right;
} else {
return null;
}
}
...
return myRoot;
}
I have written the following pseudocode for a removeNode() method while working with BST's:
If left is null
Replace n with n.right
Else if n.right is null
Replace n with n.left
Else
Find Predecessor of n
Copy data from predecessor to n
Recursively delete predecessor*
Not only do I want this method to delete or remove Nodes, but I also want it to return true if the deletion is successful.
This is what I have written so far, and I was wondering if anyone would have feedback, suggested changes, or tips to help me complete the method. I will also attach my whole program below this method.
private void removeNode(Node<E> n) {
if (n.left == null) {
replace(n, n.right);
} else if (n.right == null) {
replace(n, n.left);
} else {
//How do I find pred of n
//Copy data from pred to n
//Recursively delete pred
}
}
Here is the rest of my code:
import java.util.Random;
public class BinarySearchTree<E extends Comparable<? super E>> extends BinaryTree<E> {
public boolean contains(E item) {
return findNode(item, root) != null;
}
private Node<E> findNode(E item, Node<E> n) {
if (n == null || item == null) return null;
int result = item.compareTo(n.data);
if (result == 0) {
return n;
} else if (result > 0) {
return findNode(item, n.right);
} else {
return findNode(item, n.left);
}
}
public E max() {
Node<E> m = maxNode(root);
return (m != null) ? m.data : null;
}
private Node<E> maxNode(Node<E> n) {
if (n == null) return null;
if (n.right == null) return n;
return maxNode(n.right);
}
public E min() {
Node<E> m = minNode(root);
return (m != null) ? m.data : null;
}
private Node<E> minNode(Node<E> n) {
if (n == null) return null;
if (n.left == null) return n;
return minNode(n.left);
}
public E pred(E item) {
Node<E> n = findNode(item, root);
if (n == null) return null;
Node<E> pred = predNode(n);
return (pred != null) ? pred.data : null;
}
private Node<E> predNode(Node<E> n) {
assert n != null;
if (n.left != null) return maxNode(n.left);
Node<E> p = n.parent;
while (p != null && p.left == n) {
n = p;
p = p.parent;
}
return p;
}
public E succ(E item) {
Node<E> n = findNode(item, root);
if (n == null) return null;
Node<E> succ = succNode(n);
return (succ != null) ? succ.data : null;
}
private Node<E> succNode(Node<E> n) {
assert n != null;
if (n.right != null) return minNode(n.right);
Node<E> p = n.parent;
while (p != null && p.right == n) {
n = p;
p = p.parent;
}
return p;
}
public void add(E item) {
if (item == null) return;
if (root == null) {
root = new Node<>(item, null);
} else {
addNode(item, root);
}
}
private void addNode(E item, Node<E> n) {
assert item != null && n != null;
int result = item.compareTo(n.data);
if (result < 0) {
if (n.left == null) {
n.left = new Node<>(item, n);
} else {
addNode(item, n.left);
}
} else if (result > 0) {
if (n.right == null) {
n.right = new Node<>(item, n);
} else {
addNode(item, n.right);
}
} else {
return; // do not add duplicates
}
}
public boolean remove(E item) {
Node<E> n = findNode(item, root);
if (n == null) return false;
removeNode(n);
return true;
}
private void removeNode(Node<E> n) {
if (n.left == null) {
replace(n, n.right);
} else if (n.right == null) {
replace(n, n.left);
} else {
//How do I find pred of n
//Copy data from pred to n
//Recursively delete pred
}
}
private void replace(Node<E> n, Node<E> child) {
assert n != null;
Node<E> parent = n.parent;
if (parent == null) {
root = child;
} else if (parent.left == n) {
parent.left = child;
} else {
parent.right = child;
}
if (child != null) child.parent = parent;
}
public String toString() {
return inorder();
}
The code to remove an element is very straightforward.
Search for the node you want to remove.
Check if the node has children.
Case 1 - Has Only left child -> Replace current node with left child.
Case 2 - Has Only right child -> Replace current node with right child.
Case 3 - Has both children -> Find smallest element in right child subtree, replace current node with that node and then delete that node.
The Code can be implemented recursively as follows ->
BinarySearchTree.prototype.remove = function(data) {
var that = this;
var remove = function(node,data){
if(node.data === data){
if(!node.left && !node.right){
return null;
}
if(!node.left){
return node.right;
}
if(!node.right){
return node.left;
}
//2 children
var temp = that.findMin(node.right);
node.data = temp;
node.right = remove(node.right,temp);
}else if(data < node.data){
node.left = remove(node.left,data);
return node;
}else{
node.right = remove(node.right,data);
return node;
}
};
this.root = remove(this.root,data);
};
I am posting new question with my code. I am trying to count the non-leaf nodes of a binary search tree. I am creating the non-leaf method and then I am trying to call it in a test class. Can someone help me? Here is the code:
public class BST {
private Node<Integer> root;
public BST() {
root = null;
}
public boolean insert(Integer i) {
Node<Integer> parent = root, child = root;
boolean gLeft = false;
while (child != null && i.compareTo(child.data) != 0) {
parent = child;
if (i.compareTo(child.data) < 0) {
child = child.left;
gLeft = true;
} else {
child = child.right;
gLeft = false;
}
}
if (child != null)
return false;
else {
Node<Integer> leaf = new Node<Integer>(i);
if (parent == null)
root = leaf;
else if (gLeft)
parent.left = leaf;
else
parent.right = leaf;
return true;
}
}
public boolean find(Integer i) {
Node<Integer> n = root;
boolean found = false;
while (n != null && !found) {
int comp = i.compareTo(n.data);
if (comp == 0)
found = true;
else if (comp < 0)
n = n.left;
else
n = n.right;
}
return found;
}
public int nonleaf() {
int count = 0;
Node<Integer> parent = root;
if (parent == null)
return 0;
if (parent.left == null && parent.right == null)
return 1;
}
}
class Node<T> {
T data;
Node<T> left, right;
Node(T o) {
data = o;
left = right = null;
}
}
If you are interested in only count of non-leaf node then you can traverse tree once and maintain one count. whenever you encounter a node such that it has either left or right node increment count.
You can use the following function to count number of non-leaf nodes of binary tree.
int countNonLeafNodes(Node root)
{
if (root == null || (root.left == null &&
root.right == null))
return 0;
return 1 + countNonLeafNodes(root.left) +
countNonLeafNodes(root.right);
}
I am trying to implement BST algorithm using Cormen's pseudo code yet having issue.
Here is my Code for Node:
public class Node {
Node left;
Node right;
int value;
Node(int value){
this.value = value;
this.left = null;
this.right = null;
}
}
and for the Bstree:
public class Btree {
Node root;
Btree(){
this.root = null;
}
public static void inorderWalk(Node n){
if(n != null){
inorderWalk(n.left);
System.out.print(n.value + " ");
inorderWalk(n.right);
}
}
public static Node getParent(Btree t, Node n){
Node current = t.root;
Node parent = null;
while(true){
if (current == null)
return null;
if( current.value == n.value ){
break;
}
if (current.value > n.value){
parent = current;
current = current.left;
}
else{ //(current.value < n.value)
parent = current;
current = current.right;
}
}
return parent;
}
public static Node search(Node n,int key){
if(n == null || key == n.value ){
return n;
}
if(key < n.value){
return search(n.left,key);
}
else{
return search(n.right,key);
}
}
public static Node treeMinimum(Node x){
if(x == null){
return null;
}
while(x.left != null){
x = x.left;
}
return x;
}
public static Node treeMaximum(Node x){
if(x == null){
return null;
}
while(x.right != null){
x = x.right;
}
return x;
}
public static Node treeSuccessor(Btree t,Node x){
if (x.right == null){
return treeMinimum(x.right);
}
Node y = getParent(t,x);
while(y != null && x == y.right){
x = y;
y = getParent(t,y);
}
return y;
}
public static Btree insert(Btree t,Node z){
Node y = null;
Node x = t.root;
while(x != null){
y = x;
if(z.value < x.value)
x = x.left;
else
x = x.right;
}
Node tmp = getParent(t,z);
tmp = y;
if(y == null){
t.root = z;
}
else if(z.value < y.value)
y.left = z;
else
y.right = z;
return t;
}
public static Btree delete(Btree t,Node z){
Node y,x;
if (z.left == null || z.right == null)
y = z;
else
y = treeSuccessor(t,z);
if (y.left != null)
x = y.left;
else
x = y.right;
if (x != null){
Node tmp = getParent(t,x);
tmp = getParent(t,y);
}
if (getParent(t,y) == null ){
t.root = x;
}
else{
if( y == getParent(t,y).left ){
getParent(t,y).left = x;
}
else{
getParent(t,y).right = x;
}
}
if(y != z){
z.value = y.value;
}
return t;
}
public static void main(String[] args){
Btree test = new Btree();
Node n1 = new Node(6);
Node n2 = new Node(3);
Node n3 = new Node(9);
Node n4 = new Node(1);
Node n5 = new Node(16);
Node n6 = new Node(4);
Node n7 = new Node(2);
Node n8 = new Node(11);
Node n9 = new Node(13);
test = insert(test,n1);
test = insert(test,n2);
test = insert(test,n3);
test = insert(test,n4);
test = insert(test,n5);
test = insert(test,n6);
test = insert(test,n7);
test = insert(test,n8);
test = insert(test,n9);
inorderWalk(test.root);
System.out.println();
test = delete(test,n8);
inorderWalk(test.root);
System.out.println();
test = delete(test,n5);
inorderWalk(test.root);
System.out.println();
test = delete(test,n2);
inorderWalk(test.root);
System.out.println();
test = delete(test,n1);
inorderWalk(test.root);
}
}
The main problem is with the remove part, sometimes it is working as intended, sometimes removing wrongly and sometimes null pointer exception. What can be the issue ?
Ps: this is NOT a homework
Some immediate problems with your code: your treeSuccessor starts with
if (x.right == null){
return treeMinimum(x.right);
}
which should be if (x.right != null), of course.
Your insert code has the lines
Node tmp = getParent(t,z);
tmp = y;
where you assign to tmp and immediately assign to it again. It doesn't seem to me that you need these lines at all, since you don't use tmp further on. At this moment, you have y being the node to whose child z gets inserted, so just delete these lines.
Again, in delete, you have the lines
if (x != null){
Node tmp = getParent(t,x);
tmp = getParent(t,y);
}
where you don't actually do anything, since tmp is not visible outside this snippet. And further on, in delete, you repeat the expression getParent(t,y), which can be an expensive operation, so you should compute it only once and assign it to some variable.
But in general, your code, though it seems correct (probably apart from delete, which I did not understand completely but which looks suspicious), does not much resemble typical binary tree code. You don't really need the getParent and treeSuccessor methods to implement search, insert, and delete. The basic structure that you have for search works for the others too, with the following modifications:
with insert, when you get to a null link, instead of returning null, insert the element to that point
with delete, when you find the element, if it has only one (or no) child, replace it with that child, and if it has two children, replace it with either the maximum of the left child tree or the minimum of the right child tree
Both of these require in addition that you keep track of the parent node while descending into the tree, but that's the only modification you need to make to search. In particular, there is never any need to go upwards in the tree (which treeSuccessor will do).
First of all, your implementation got nothing to do with object orientation (except using objects). The insert and delete operations for example should operate ON the Tree.
Besides, I would recommend to implement the Node class as a static member of the Tree class.
public class Tree {
private Node root = null;
// remainder omitted
public boolean insert(int element) {
if (isEmpty()) {
root = new Node(element);
return true; // empty tree, Node could be inserted, return true
}
Node current = root; // start at root
Node parent; // the current Node's parent
do {
parent = current;
if (element < current.element) {
current = current.left; // go to left
} else if (element > current.element) {
current = current.right; // go to right
} else {
return false; // duplicates are NOT allowed, element could not be inserted -> return false
} while (current != null);
Node node = new Node(element);
if (element < current.element) {
parent.left = node;
} else {
parent.right = node;
}
return true; // node successfully inserted
}
public boolean isEmpty() {
return root == null;
}
private static class Node { // static member class
Node left = null;
Node right = null;
final int element;
Node(int element) {
this.element = element;
}
}
}
...what is up with your delete code? It doesn't make a lot of sense. I would consider rewriting it in a more logical way. Without the meaningless single-letter variable names. And add comments!
One possible algorithm is:
Get the parent of the node to delete
Get the right-most node of the left subtree, or the leftmost node of the right subtree
Remove the node to delete and replace it with the node you found
Rebalance the tree
...or, if you want to hack up this stuff so it's right, I'd start looking at the
if (x != null){
Node tmp = getParent(t,x);
tmp = getParent(t,y);
}
part, because that's clearly wrong.
I'll have to side with Anon and go for the rewrite. The null pointers come from your getParent function (which explicitly returns nulls along other things). So I would start there and fix the function(s) so that they return one thing and one thing only at the end of the function.
Here is the complete Implementation of Binary Search Tree In Java
insert,search,countNodes,traversal,delete,empty,maximum & minimum node,find parent node,print all leaf node, get level,get height, get depth,print left view, mirror view
import java.util.NoSuchElementException;
import java.util.Scanner;
import org.junit.experimental.max.MaxCore;
class BSTNode {
BSTNode left = null;
BSTNode rigth = null;
int data = 0;
public BSTNode() {
super();
}
public BSTNode(int data) {
this.left = null;
this.rigth = null;
this.data = data;
}
#Override
public String toString() {
return "BSTNode [left=" + left + ", rigth=" + rigth + ", data=" + data + "]";
}
}
class BinarySearchTree {
BSTNode root = null;
public BinarySearchTree() {
}
public void insert(int data) {
BSTNode node = new BSTNode(data);
if (root == null) {
root = node;
return;
}
BSTNode currentNode = root;
BSTNode parentNode = null;
while (true) {
parentNode = currentNode;
if (currentNode.data == data)
throw new IllegalArgumentException("Duplicates nodes note allowed in Binary Search Tree");
if (currentNode.data > data) {
currentNode = currentNode.left;
if (currentNode == null) {
parentNode.left = node;
return;
}
} else {
currentNode = currentNode.rigth;
if (currentNode == null) {
parentNode.rigth = node;
return;
}
}
}
}
public int countNodes() {
return countNodes(root);
}
private int countNodes(BSTNode node) {
if (node == null) {
return 0;
} else {
int count = 1;
count += countNodes(node.left);
count += countNodes(node.rigth);
return count;
}
}
public boolean searchNode(int data) {
if (empty())
return empty();
return searchNode(data, root);
}
public boolean searchNode(int data, BSTNode node) {
if (node != null) {
if (node.data == data)
return true;
else if (node.data > data)
return searchNode(data, node.left);
else if (node.data < data)
return searchNode(data, node.rigth);
}
return false;
}
public boolean delete(int data) {
if (empty())
throw new NoSuchElementException("Tree is Empty");
BSTNode currentNode = root;
BSTNode parentNode = root;
boolean isLeftChild = false;
while (currentNode.data != data) {
parentNode = currentNode;
if (currentNode.data > data) {
isLeftChild = true;
currentNode = currentNode.left;
} else if (currentNode.data < data) {
isLeftChild = false;
currentNode = currentNode.rigth;
}
if (currentNode == null)
return false;
}
// CASE 1: node with no child
if (currentNode.left == null && currentNode.rigth == null) {
if (currentNode == root)
root = null;
if (isLeftChild)
parentNode.left = null;
else
parentNode.rigth = null;
}
// CASE 2: if node with only one child
else if (currentNode.left != null && currentNode.rigth == null) {
if (root == currentNode) {
root = currentNode.left;
}
if (isLeftChild)
parentNode.left = currentNode.left;
else
parentNode.rigth = currentNode.left;
} else if (currentNode.rigth != null && currentNode.left == null) {
if (root == currentNode)
root = currentNode.rigth;
if (isLeftChild)
parentNode.left = currentNode.rigth;
else
parentNode.rigth = currentNode.rigth;
}
// CASE 3: node with two child
else if (currentNode.left != null && currentNode.rigth != null) {
// Now we have to find minimum element in rigth sub tree
// that is called successor
BSTNode successor = getSuccessor(currentNode);
if (currentNode == root)
root = successor;
if (isLeftChild)
parentNode.left = successor;
else
parentNode.rigth = successor;
successor.left = currentNode.left;
}
return true;
}
private BSTNode getSuccessor(BSTNode deleteNode) {
BSTNode successor = null;
BSTNode parentSuccessor = null;
BSTNode currentNode = deleteNode.left;
while (currentNode != null) {
parentSuccessor = successor;
successor = currentNode;
currentNode = currentNode.left;
}
if (successor != deleteNode.rigth) {
parentSuccessor.left = successor.left;
successor.rigth = deleteNode.rigth;
}
return successor;
}
public int nodeWithMinimumValue() {
return nodeWithMinimumValue(root);
}
private int nodeWithMinimumValue(BSTNode node) {
if (node.left != null)
return nodeWithMinimumValue(node.left);
return node.data;
}
public int nodewithMaximumValue() {
return nodewithMaximumValue(root);
}
private int nodewithMaximumValue(BSTNode node) {
if (node.rigth != null)
return nodewithMaximumValue(node.rigth);
return node.data;
}
public int parent(int data) {
return parent(root, data);
}
private int parent(BSTNode node, int data) {
if (empty())
throw new IllegalArgumentException("Empty");
if (root.data == data)
throw new IllegalArgumentException("No Parent node found");
BSTNode parent = null;
BSTNode current = node;
while (current.data != data) {
parent = current;
if (current.data > data)
current = current.left;
else
current = current.rigth;
if (current == null)
throw new IllegalArgumentException(data + " is not a node in tree");
}
return parent.data;
}
public int sibling(int data) {
return sibling(root, data);
}
private int sibling(BSTNode node, int data) {
if (empty())
throw new IllegalArgumentException("Empty");
if (root.data == data)
throw new IllegalArgumentException("No Parent node found");
BSTNode cureent = node;
BSTNode parent = null;
boolean isLeft = false;
while (cureent.data != data) {
parent = cureent;
if (cureent.data > data) {
cureent = cureent.left;
isLeft = true;
} else {
cureent = cureent.rigth;
isLeft = false;
}
if (cureent == null)
throw new IllegalArgumentException("No Parent node found");
}
if (isLeft) {
if (parent.rigth != null) {
return parent.rigth.data;
} else
throw new IllegalArgumentException("No Sibling is there");
} else {
if (parent.left != null)
return parent.left.data;
else
throw new IllegalArgumentException("No Sibling is there");
}
}
public void leafNodes() {
if (empty())
throw new IllegalArgumentException("Empty");
leafNode(root);
}
private void leafNode(BSTNode node) {
if (node == null)
return;
if (node.rigth == null && node.left == null)
System.out.print(node.data + " ");
leafNode(node.left);
leafNode(node.rigth);
}
public int level(int data) {
if (empty())
throw new IllegalArgumentException("Empty");
return level(root, data, 1);
}
private int level(BSTNode node, int data, int level) {
if (node == null)
return 0;
if (node.data == data)
return level;
int result = level(node.left, data, level + 1);
if (result != 0)
return result;
result = level(node.rigth, data, level + 1);
return result;
}
public int depth() {
return depth(root);
}
private int depth(BSTNode node) {
if (node == null)
return 0;
else
return 1 + Math.max(depth(node.left), depth(node.rigth));
}
public int height() {
return height(root);
}
private int height(BSTNode node) {
if (node == null)
return 0;
else
return 1 + Math.max(height(node.left), height(node.rigth));
}
public void leftView() {
leftView(root);
}
private void leftView(BSTNode node) {
if (node == null)
return;
int height = height(node);
for (int i = 1; i <= height; i++) {
printLeftView(node, i);
}
}
private boolean printLeftView(BSTNode node, int level) {
if (node == null)
return false;
if (level == 1) {
System.out.print(node.data + " ");
return true;
} else {
boolean left = printLeftView(node.left, level - 1);
if (left)
return true;
else
return printLeftView(node.rigth, level - 1);
}
}
public void mirroeView() {
BSTNode node = mirroeView(root);
preorder(node);
System.out.println();
inorder(node);
System.out.println();
postorder(node);
System.out.println();
}
private BSTNode mirroeView(BSTNode node) {
if (node == null || (node.left == null && node.rigth == null))
return node;
BSTNode temp = node.left;
node.left = node.rigth;
node.rigth = temp;
mirroeView(node.left);
mirroeView(node.rigth);
return node;
}
public void preorder() {
preorder(root);
}
private void preorder(BSTNode node) {
if (node != null) {
System.out.print(node.data + " ");
preorder(node.left);
preorder(node.rigth);
}
}
public void inorder() {
inorder(root);
}
private void inorder(BSTNode node) {
if (node != null) {
inorder(node.left);
System.out.print(node.data + " ");
inorder(node.rigth);
}
}
public void postorder() {
postorder(root);
}
private void postorder(BSTNode node) {
if (node != null) {
postorder(node.left);
postorder(node.rigth);
System.out.print(node.data + " ");
}
}
public boolean empty() {
return root == null;
}
}
public class BinarySearchTreeTest {
public static void main(String[] l) {
System.out.println("Weleome to Binary Search Tree");
Scanner scanner = new Scanner(System.in);
boolean yes = true;
BinarySearchTree tree = new BinarySearchTree();
do {
System.out.println("\n1. Insert");
System.out.println("2. Search Node");
System.out.println("3. Count Node");
System.out.println("4. Empty Status");
System.out.println("5. Delete Node");
System.out.println("6. Node with Minimum Value");
System.out.println("7. Node with Maximum Value");
System.out.println("8. Find Parent node");
System.out.println("9. Count no of links");
System.out.println("10. Get the sibling of any node");
System.out.println("11. Print all the leaf node");
System.out.println("12. Get the level of node");
System.out.println("13. Depth of the tree");
System.out.println("14. Height of Binary Tree");
System.out.println("15. Left View");
System.out.println("16. Mirror Image of Binary Tree");
System.out.println("Enter Your Choice :: ");
int choice = scanner.nextInt();
switch (choice) {
case 1:
try {
System.out.println("Enter Value");
tree.insert(scanner.nextInt());
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 2:
System.out.println("Enter the node");
System.out.println(tree.searchNode(scanner.nextInt()));
break;
case 3:
System.out.println(tree.countNodes());
break;
case 4:
System.out.println(tree.empty());
break;
case 5:
try {
System.out.println("Enter the node");
System.out.println(tree.delete(scanner.nextInt()));
} catch (Exception e) {
System.out.println(e.getMessage());
}
case 6:
try {
System.out.println(tree.nodeWithMinimumValue());
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 7:
try {
System.out.println(tree.nodewithMaximumValue());
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 8:
try {
System.out.println("Enter the node");
System.out.println(tree.parent(scanner.nextInt()));
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 9:
try {
System.out.println(tree.countNodes() - 1);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 10:
try {
System.out.println("Enter the node");
System.out.println(tree.sibling(scanner.nextInt()));
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 11:
try {
tree.leafNodes();
} catch (Exception e) {
System.out.println(e.getMessage());
}
case 12:
try {
System.out.println("Enter the node");
System.out.println("Level is : " + tree.level(scanner.nextInt()));
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 13:
try {
System.out.println(tree.depth());
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 14:
try {
System.out.println(tree.height());
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 15:
try {
tree.leftView();
System.out.println();
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 16:
try {
tree.mirroeView();
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
default:
break;
}
tree.preorder();
System.out.println();
tree.inorder();
System.out.println();
tree.postorder();
} while (yes);
scanner.close();
}
}
As per my understanding following implementation done for binary search tree, kindly look
into that and let me know any feedback required
Insertion
InOrderTraversal
Search
Removal
Please take a look at the main method. so, Please provide your's feedback to improve further from my side.
public class BinarySearchTree {
private Node root;
public BinarySearchTree() {
root = null;
}
public BinarySearchTree(int rootData) {
root = new Node(rootData);
}
public void insertElement(int element,Node parent) {
Node temp = root;
if(parent!=null) temp = parent;
if(temp!=null) {
Node node = new Node(element);
if(element<temp.getData()) {
if(temp.getLeft()!=null)
insertElement(element, temp.getLeft());
else
temp.setLeft(node);
}else if(element>temp.getData()) {
if(temp.getRight()!=null)
insertElement(element, temp.getRight());
else
temp.setRight(node);
}
}
}
public void traverseInOrder() {
if(root!=null) {
traverse(root.getLeft());
System.out.println(root.getData());
traverse(root.getRight());
}
}
public void traverse(Node temp) {
if(temp!=null) {
traverse(temp.getLeft());
System.out.println(temp.getData());
traverse(temp.getRight());
}
}
public int searchElement(int element,Node node) {
Node temp = root;
if(node!=null) temp = node;
if(temp!=null) {
if(temp.getData()<element) {
if(temp.getRight()!=null)
return searchElement(element, temp.getRight());
}else if(temp.getData()>element) {
if(temp.getLeft()!=null)
return searchElement(element,temp.getLeft());
}else if(temp.getData()==element){
return temp.getData();
}
}
return -1;
}
public void remove(int element,Node node,Node predecer) {
Node temp = root;
if(node!=null) temp = node;
if(temp!=null) {
if(temp.getData()>element) {
remove(element, temp.getLeft(), temp);
}else if(temp.getData()<element) {
remove(element, temp.getRight(), temp);
}else if(element==temp.getData()) {
if(temp.getLeft()==null && temp.getRight()==null) {
if(predecer.getData()>temp.getData()) {
predecer.setLeft(null);
}else if(predecer.getData()<temp.getData()) {
predecer.setRight(null);
}
}else if(temp.getLeft()!=null && temp.getRight()==null) {
predecer.setRight(temp.getLeft());
}else if(temp.getLeft()==null && temp.getRight()!=null) {
predecer.setLeft(temp.getRight());
}else if(temp.getLeft()!=null && temp.getRight()!=null) {
Node leftMostElement = findMaximumLeft(temp.getLeft());
if(leftMostElement!=null) {
remove(leftMostElement.getData(), temp, temp);
temp.setData(leftMostElement.getData());
}
}
}
}
}
public Node findMaximumLeft(Node parent) {
Node temp = parent;
if(temp.getRight()!=null)
return findMaximumLeft(temp.getRight());
else
return temp;
}
public static void main(String[] args) {
BinarySearchTree bs = new BinarySearchTree(10);
bs.insertElement(29, null);
bs.insertElement(19, null);
bs.insertElement(209, null);
bs.insertElement(6, null);
bs.insertElement(7, null);
bs.insertElement(17, null);
bs.insertElement(37, null);
bs.insertElement(67, null);
bs.insertElement(-7, null);
bs.remove(6, null, null);
bs.traverseInOrder();}}